The Washington Post article caught my eye, “Minimalist running style may be undermined by new findings from Kenya.” The January 21 article by Lenny Bernstein on the web was about a new study published at PLOS One.

Bernstein starts the article with a figure that catches your attention, Americans spent $59 million on “minimalist” running shoes last year, on the premise that the most healthful way to run is the way people have done it for thousands of years: barefoot.

Years after runners everywhere were introduce to running barefoot in 2009 in Born to Run and a 2010 study of Kenya’s famous Kalenjin distance runners, the new study may cause some to rethink how they run.

In the new study, a group of George Washington University researchers tested a different population of barefoot African runners and determined that most of them naturally strike the ground with their heels.

The study measured subjects running along a trackway at least three times at their self-selected (comfortable) endurance running pace, and three more times at a faster pace. The track had a plantar pressure pad placed midway along its length.

Close-up images of subjects using a rearfoot strike (A) and a midfoot strike (B).

The article quotes Kevin Hatala, a doctoral student in anthropology at GWU, and how they expected the group’s study of 38 Daasanach subjects of northern Kenya to support Harvard researcher’s Daniel Lieberman’s conclusions about the Kalenjin. Hatala said, “Instead, we found the opposite to be true. In the group we were looking at, the majority of them were rear-foot striking at their preferred endurance running speed.”

Bernstein wrote, At higher speeds, some of the Daasanach switched from a heel strike to a forefoot strike, but even then, heel-striking was more typical. Hatala was reluctant to speculate why his findings differed from the prevailing wisdom. In addition to the effect of speed, running style could be the result of information that is culturally transmitted from generation to generation. Or it might have something to do with the predominant surface where each group lives. Hatala and Lieberman are at the early stages of comparing their data.

“I guess what we found really interesting about this is it directly shows that there is not one way to run barefoot,” Hatala said. “We have a lot more to learn about how people who are barefoot run and what might be the best way to run barefoot.”

The abstract for the study says, “Our data supports the hypothesis that a forefoot strike reduces the magnitude of impact loading, but the majority of subjects instead used a rearfoot strike at endurance running speeds. Their percentages of midfoot and forefoot strikes increased significantly with speed. These results indicate that not all habitually barefoot people prefer running with a forefoot strike, and suggest that other factors such as running speed, training level, substrate mechanical properties, running distance, and running frequency, influence the selection of foot strike patterns.”

Sales of minimalist shoes are up 303 percent between November 2010 and November 2012, compared with a 19 percent increase in running shoe sales overall in the same period.

Are you a barefoot runner? If so, what is your foot strike pattern when running – forefoot, midfoot, or rearfoot? And importantly, does your foot strike change as your pace changes?